With reference to FIG. 1, a large assortment of smoke and/or CO alarms 103 is available in any hardware store. These units are generally reliable and affordable. They often operate for a year or more on one inexpensive battery. If alarm or hazard conditions occur (for example, smoke 105, unauthorized entry or high CO concentration) they are often designed to produce a high pitched, ear piercing sound 104, loud enough to awaken most people in the immediate vicinity.
Many residential and commercial buildings are heated by forced air furnaces 101, fueled by natural gas, or oil. These units (as well as water heaters 102) are typically located in basements or utility rooms, which are quite often acoustically insulated from the rest of the premises. Malfunction of furnaces 101 and water heaters 102 are common causes of fires and/or carbon monoxide poisoning. Placing typical alarm devices 103 (as described above) in these areas offers less than desired protection, because the sound 104 is generally not effectively transmitted to dwelling areas 106. Alarm systems do exist, that feature remote sound sources, linked to the actual alarm sensors through wires, or through radio-frequency transmitters. This adds much to the cost and to the needed maintenance.
There is therefore a need for an effective and highly economical broadcasting hazard alarm system.